package com.mzj.saas.commons.util;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Base64;

public class Base64Utils {
	/**
	 * 文件读取缓冲区大小
	 */
	private static final int CACHE_SIZE = 1024;

	/**
	 * <p>
	 * BASE64字符串解码为二进制数据
	 * </p>
	 * 
	 * @param base64
	 * @return
	 * @throws Exception
	 */
	public static byte[] decode(String base64) throws Exception {
		return Base64.getDecoder().decode(base64.getBytes());
	}

	/**
	 * <p>
	 * 二进制数据编码为BASE64字符串
	 * </p>
	 *
	 * @param bytes
	 * @return
	 * @throws Exception
	 */
	public static String encode(byte[] bytes) throws Exception {

		return new String(Base64.getEncoder().encode(bytes));

	}

	/**
	 * <p>
	 * 将文件编码为BASE64字符串
	 * </p>
	 * <p>
	 * 大文件慎用，可能会导致内存溢出
	 * </p>
	 *
	 * @param filePath 文件绝对路径
	 * @return
	 * @throws Exception
	 */
	public static String encodeFile(String filePath) throws Exception {

		byte[] bytes = fileToByte(filePath);
		return encode(bytes);

	}

	/**
	 * <p>
	 * BASE64字符串转回文件
	 * </p>
	 *
	 * @param filePath 文件绝对路径
	 * @param base64   编码字符串
	 * @throws Exception
	 */
	public static void decodeToFile(String filePath, String base64) throws Exception {

		byte[] bytes = decode(base64);
		byteArrayToFile(bytes, filePath);

	}

	/**
	 * <p>
	 * 文件转换为二进制数组
	 * </p>
	 *
	 * @param filePath 文件路径
	 * @return
	 * @throws Exception
	 */
	public static byte[] fileToByte(String filePath) throws Exception {

		byte[] data = new byte[0];
		File file = new File(filePath);
		if (file.exists()) {

			FileInputStream in = new FileInputStream(file);
			ByteArrayOutputStream out = new ByteArrayOutputStream(2048);
			byte[] cache = new byte[CACHE_SIZE];
			int nRead = 0;
			while ((nRead = in.read(cache)) != -1) {

				out.write(cache, 0, nRead);
				out.flush();

			}
			out.close();
			in.close();
			data = out.toByteArray();

		}
		return data;

	}

	/**
	 * <p>
	 * 二进制数据写文件
	 * </p>
	 *
	 * @param bytes    二进制数据
	 * @param filePath 文件生成目录
	 */
	public static void byteArrayToFile(byte[] bytes, String filePath) throws Exception {

		InputStream in = new ByteArrayInputStream(bytes);
		File destFile = new File(filePath);
		if (!destFile.getParentFile().exists()) {

			destFile.getParentFile().mkdirs();

		}
		destFile.createNewFile();
		OutputStream out = new FileOutputStream(destFile);
		byte[] cache = new byte[CACHE_SIZE];
		int nRead = 0;
		while ((nRead = in.read(cache)) != -1) {

			out.write(cache, 0, nRead);
			out.flush();

		}
		out.close();
		in.close();

	}

	public static String getFromBase64(String s) {
		byte[] b = null;
		String result = null;
		if (s != null) {
			try {
				b = Base64.getDecoder().decode(s);//
				result = new String(b, "utf-8");
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		return result;
	}
}
